Sunday, August 11, 2013

Hanukkah and Thanksgiving: A once in eternity overlap

This year features an anomaly for American Jews – The first day of Hanukkah coincides with Thanksgiving, on 11/28/2013.
It turns out that it has never happened before...and it will never happen again.

Thanksgiving is set as the fourth Thursday in November, meaning the latest it can be is 11/28. 11/28 is also the earliest Hanukkah can be. The Jewish calendar repeats on a 19 year cycle, and Thanksgiving repeats on a 7 year cycle. You would therefore expect them to coincide roughly every 19x7 = 133 years. Looking back, this is approximately correct – the last time it would have happened is 1861. However, Thanksgiving was only formally established by President Lincoln in 1863. So, it has never happened before. Why won't it ever happen again?

The reason is because the Jewish calendar is very slowly getting out of sync with the solar calendar, at a rate of 4 days per 1000 years (not bad for a many centuries old calendar!) This means that while presently Hanukkah can be as early as 11/28, over the years the calendar will drift forward, such that the earliest Hanukkah can be is 11/29. The last time Hanukkah falls on 11/28 is 2146 (which happens to be a Monday). Therefore, 2013 is the only time Hanukkah will ever overlap with Thanksgiving.

Of course, if the Jewish calendar is never modified in any way, then it will slowly move forward through the Gregorian calendar, until it loops all the way back to where it is now. So, Hanukkah will again fall on Thursday, 11/ the year 79,811.

Written by Lena Lieb, of the Evelyn Rubenstein JCC - Houston, Texas


  1. No one seems the least bit worried about the calendar getting out of sync, even though keeping it in sync is the first mitzvah in the Torah! :) I guess everyone figures Moshiach will come by then.

  2. Well, that's the thing, because of leap years, it won't get out of sync.

    The way I see it, this piece is flawed, because if it does move up through the months over time, then Chanukah is bound to fall out on Thanksgiving again.

    Its only if we keep with the current calendar schedule, and cycle, that it won't fall out again on Thanksgiving until 2146.

    At least that's what I think.

  3. Even with leap years it will indeed get out of sync, just very slowly. The calendar we use with its built-in leap years is quite accurate, but not accurate enough. Eventually Pesach will be in the summer. (Not for a loooooong time).

    1. Not if we go back to the basis din establishing when rosh chodesh is.

    2. Yeah, no one will accept that these days, because we are too loosely "governed".


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